Apparatus and methods for sequestering fluids exhausted during fluid transfer

ABSTRACT

A liquid transfer connector comprises an enclosure holding a transfer needle and an exhaust needle. A container of donor liquid may be attached to an inlet end of the transfer needle and a container holding a recipient liquid may be attached to an outlet end of the transfer needle and an inlet end of an exhaust needle. The exhaust needle has an outlet end within the connector which releases displaced fluid into an absorbent mass which sequesters the fluid to prevent leakage.

CROSS-REFERENCES TO RELATED APPLICATIONS

The present application claims the benefit of provisional No. 61/458,002(attorney docket number 36312-713.101), filed on Nov. 15, 2010, the fulldisclosure of which is incorporated herein by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates generally to methods and apparatus forcombining parenteral solutions and other liquids. More particularly, thepresent invention relates to methods for transferring a donor liquidinto a recipient container filled with a recipient liquid where excessliquid in the recipient container is exhausted from the recipientcontainer and captured.

Commonly-owned copending application US 2009/0292271, the fulldisclosure of which is incorporated herein by reference, describes a“dosing pen” device capable of combining liquid buffers and anesthetics.The dosing pen includes a fluid transfer device which utilizes atransfer needle 36 (the reference numbers in this paragraph refer to the'271 publication) and an exhaust needle 38 positioned in a knob 12 whichcan removably receive an anesthetic cartridge 28 so that distal ends ofboth the transfer needle and exhaust needle penetrate a septum on theanesthetic cartridge. A buffer cartridge 16 positioned within a housing14 is also attached to the knob 12 so that a proximal end 50 of thetransfer needle 36 can penetrate a septum 15 of the buffer cartridgewhen the knob is fully advanced onto the housing. A pusher 20 isprovided to drive a plunger 58 on the buffer cartridge to transferbuffer through transfer needle 36 into the anesthetic cartridge 28 andto simultaneously exhaust anesthetic from the anesthetic cartridge backinto a reservoir 72 in the housing 14 through the exhaust needle 38.While the dosing pen of the '271 application is advantageous in manyrespects, the excess buffer, which is exhausted through exhaust needle38, ends up in the housing 14 and is subject to leakage.

An improved dosing pen is described in commonly owned US2011/0166543,the full disclosure of which is incorporated herein by reference. Asillustrated in FIG. 1 herein, the '543 publication shows a dosingassembly 10 which connects a buffer cartridge 12 and an anestheticcartridge 14 with a transfer needle 16 entering through septum 18 andseptum 20, respectively. An exhaust needle penetrates septum 20 of theanesthetic cartridge and allows excess anesthetic to vent into acollection reservoir 26 in a housing 24 which hold the needles. Thechamber is “sealed” and intended to be contain the excess liquid 28 toprevent leakage. While certainly an improvement, the chamber willusually need at least a small vent to permit the displacement of airinitially present in the chamber and remains subject to leakage as thedosing pen is manipulated and reoriented, particularly when a newanesthetic cartridge is being exchanged for a buffered anestheticcartridge. Even if leakage through the vent were inhibited, for exampleusing a gas permeable liquid barrier over the vent, there is still arisk that pooled liquid within the chamber could submerge the outlet endof the exhaust needle, resulting in backflow of the excess fluid.

For these reasons, it would be desirable to provide improved methods andapparatus for transferring and combining liquids, such as buffersolutions and anesthetics, where the liquids are held in conventionalcontainers with needle-penetrable septums and dispensing plungers. Inparticular, it would be desirable to provide systems and methods whichallow for transfer of a donor liquid, such as a buffer solution, into arecipient solution, such as an anesthetic, which fills a recipientcontainer where the displaced recipient solution can be vented orexhausted into a reservoir with a minimum risk of backflow or leakagefrom the reservoir. At least some of these objectives will be met by theinventions described hereinbelow.

2. Description of the Background Art

US 2011/0166543 and US2009/0292271 have been described above. Glassvials and cartridges for storing medical solutions are described in U.S.Pat. Nos. 1,757,809; 2,484,657; 4,259,956; 5,062,832; 5,137,528;5,149,320; 5,226,901; 5,330,426; and 6,022,337. Injection pens whichemploy drug cartridges are described in U.S. Pat. No. 5,984,906. Aparticular disposable drug cartridge that can find use in the presentinvention is described in U.S. Pat. No. 5,603,695. A device fordelivering a buffering agent into an anesthetic cartridge using atransfer needle is described in U.S. Pat. No. 5,603,695. Other patentsand applications of interest include U.S. Pat. Nos. 2,604,095;3,993,791; 4,154,820; 4,630,727; 4,654,204; 4,756,838; 4,959,175;5,296,242; 5,383,324; 5,603,695; 5,609,838; 5,779,357; and U.S. PatentPubl. No. 2004/0175437

BRIEF SUMMARY OF THE INVENTION

The present invention provides apparatus and methods which rapidlyabsorb liquids displaced during fluid transfer into a sealed recipientcontainer. While particularly useful when transferring a buffer solutioninto an anesthetic or other medical solution, the apparatus and methodsof the present invention will also be useful whenever a donor fluid isbeing transferred into a recipient fluid held in a closed containerwhere a volume of the recipient fluid equal to the volume of the donorfluid being transferred must be vented or exhausted from the closedcontainer. In particular, the present invention provides structures andmaterials which capture and rapidly absorb the exhausted recipient fluidso that the risk of leakage of the recipient fluid is reduced oreliminated.

Apparatus according to the present invention comprise a liquid transferconnector for providing a liquid transfer path between a donor containerhaving a needle-penetrable septum and a recipient container having aneedle-penetrable septum. The connector comprises an enclosure having aninterior chamber with a vent, typically a small orifice or a hole in awall of the chamber which allows air in the chamber to be released whilea displaced fluid is collected in the interior chamber. A transferneedle has an inlet end extending from one side of the interior chamberand an outlet end extending from another side of the chamber, where boththe inlet end and the outlet end are capable of penetrating a septum ona liquid container. Usually, the transfer needle will be straight sothat the inlet and outlet ends are disposed on opposite sides of thechamber, but in other instances the needle could be non-linear and evenU-shaped so that the “sides” of the chamber could be adjacent to eachother. The connector further includes an exhaust needle having an inletend adjacent to the outlet end of the transfer needle and an outlet endin the interior chamber. The inlet end of the exhaust needle will alsobe capable of penetrating a septum on a liquid container, but the outletend need not be. A liquid-absorptive mass is located within the interiorchamber and adapted for rapid absorption of liquid entering the interiorchamber through the exhaust needle. In this way, the liquid is capturedand sequestered within the absorptive mass so that little or no freeliquid remains in the chamber, thus reducing or eliminating the riskthat the liquid will be lost through the vent, via backflow through theexhaust needle, or in any other way.

In specific aspects of the present invention, the absorptive mass has astructure and is formed from materials which optimize the rapidabsorption of the liquid as it enters the interior chamber. Theabsorbent mass is preferably formed from a liquid-absorptive open-cellfoam having a high porosity, typically above 75% porosity, preferableabove 80% porosity, and typically 90% porosity or above, where porosityis defined as the percentage of void volume within the total volume ofthe absorptive mass. In addition to the high porosity, it is desirablethat the liquid-absorptive foam have a rapid liquid absorption rate,preferably having a liquid absorbency time of 10 seconds, or below,preferably 5 seconds or below. The liquid absorbency time may bemeasured using the methods described in IS09073-6-2000, “Textiles-Testmethods for non-wovens-Part 6: Absorption,” section 4, available fromthe International Organization of Standards, Geneva, Switzerland(www.iso.org). The test measures how rapidly a standard volume andweight of an absorptive materials can absorb liquid, where a shortertime indicates a more rapidly absorptive material. A particularlypreferred liquid-absorptive foam materials is a foam formed frompolyvinyl acetal (PVA) resin, which is a thermoplastic resin formed bythe condensation of an aldehyde with a polyvinyl alcohol. A particularlyuseful TVA foam is available from PVA Unlimited (Wausau, Indiana).

In addition to the material, the structure or geometry of theliquid-absorptive mass can also be selected to promote rapid absorptionand sequestration of the exhausted recipient liquid entering theinterior chamber of the connector. While the geometry can be as simpleas terminating an end of the exhaust needle near the center of theabsorptive mass and/or providing a plurality of outlet ports or brancheson the exhaust needle, it will be preferred to provide an interior voidwithin the absorptive mass where the outlet end of the exhaust needle isspaced-apart from the walls of the interior void so that the exhaustedrecipient liquid can pool in the void without submerging the outlet endof the exhaust needle. Such interior void provides both a retentionvolume for holding the surge of liquid which result from a liquidintroduction into the closed recipient container and a large butcontained surface area over which the exhausted recipient liquid canpenetrate into the internal pores of the absorptive mass whilecontaining the liquid within the void of the absorptive mass even priorto absorption.

In another specific aspect, the enclosure of the liquid transferconnector may comprise a cylindrical sleeve having a partition whichseparates an attachment receptacle that encloses the outlet end of thetransfer needle and the inlet end of the exhaust needle from theinterior chamber. The transfer needle may pass axially through theliquid absorptive mass, but in other embodiments could pass outside ofthe mass in either a linear or non-linear configuration. The liquidtransfer connectors may also be incorporated into the dosing pinsdescribed in commonly owned publications US2009/0292271 andUS2011/0166543, the full disclosures of which have previously beenincorporated herein by reference.

Methods according to the present invention transfer a donor liquid intoa recipient liquid present in a closed container. The methods compriseestablishing a transfer flow path from a source of the donor liquid intothe closed container which is filled with the recipient liquid,typically with little or no head space so that transfer of the donorliquid requires displacement of the recipient liquid from the closedcontainer. To displace the recipient liquid, an exhaust flow path isestablished from the closed container to an absorbent mass capable ofabsorbing and sequestering the recipient liquid. Thus, by causing avolume of the donor liquid to flow into the closed container through thetransfer flow path, a like volume of the recipient liquid is caused toflow through the exhaust flow path into the absorbent mass, where theentire volume of the exhausted recipient liquid is absorbed by theabsorbent mass.

In a specific aspect of the present invention, the outlet end oftransfer needle extends further into the recipient container than doesthe inlet end of the exhaust needle. Such an axial offset reduces therisk that the donor liquid will “short circuit” and be exhausted fromthe recipient container. Ideally, only recipient liquid will beexhausted but it is possible of course that a small amount of the donorliquid will be mixed with the exhausted recipient liquid.

As described above with respect to the apparatus of the presentinvention, the absorbent mass is usually at least partially formed froma liquid-absorptive foam where the foam has an absorptive rate less than10 seconds. Preferred liquid-absorptive foam materials comprise apolyvinyl acetal resin, and the absorptive mass preferably comprises ablock of the absorptive material having an interior void which surroundsthe outlet end of the exhaust needle.

In other specific aspects of the methods of the present invention, theabsorptive mass will have an absorptive capacity equal to at least twicethat of the volume of the exhausted recipient liquid, preferably beingat least four times as great, and often being ten times as great ormore. In this way, the absorptive mass can be used for multiple fluidtransfers, optionally where the recipient liquid container and/or adonor liquid container is replaced while using the same liquid transferconnector. Additionally, the interior void will typically have a volumeequal to at least the volume of the exhausted recipient liquid, butpreferably will have a volume equal to two, four, or more times theexpected volume of the exhausted recipient liquid. Further, the end ofthe exhaust needle will usually be spaced apart from the walls of theinterior void so that the exhausted recipient liquid can pool in thevoid without submerging the outlet end, thus reducing or eliminating therisk of backflow of the liquid into the outlet end of the exhaustneedle.

BRIEF DESCRIPTION OF THE DRAWINGS

In order to better understand the invention and to see how it may becarried out in practice, some preferred embodiments are next described,by way of non-limiting examples only, with reference to the accompanyingdrawings, in which like reference characters denote correspondingfeatures consistently throughout similar embodiments in the attacheddrawings.

FIG. 1 illustrates a prior art liquid transfer connector having a sealedliquid collection reservoir.

FIGS. 2A and 2B illustrate a liquid transfer connector constructed inaccordance with the principles of the present invention and having aliquid absorptive mass for sequestering displaced recipient liquid.

FIGS. 3A-3C illustrate alternative embodiments of the liquid absorptivemass of the present invention.

FIGS. 4A-4D illustrate how a displaced recipient liquid is absorbedwithin a liquid absorptive mass during a liquid transfer protocol inaccordance with the principles of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

Referring to FIGS. 2A and 2B, a liquid transfer connector 30 constructedin accordance with the principles of the present invention comprises anenclosure 32 having an open interior with a partition 34 separating aninterior chamber 36 from an attachment receptacle 38 (FIG. 2B). Theinterior chamber 36 is generally closed but includes vents 40 whichallow displaced gas to exit the chamber when displaced liquid enters thechamber, as described in more detail below. The vents 40 may be simpleopenings in a wall of the enclosure which are sized and shaped to permitthe passage of gas while optionally (although not necessarily)inhibiting liquid flow. Further optionally, the vents 40 may have a gaspermeable but liquid impenetrable matrix or other material therein orthereover to allow gases to vent but retain liquids.

A liquid transfer needle 42 is attached to the enclosure, typicallybeing fixed through the partition 34, such that an inlet and 44 isdisposed on one side of the interior chamber 36 and an outlet end 46 isdisposed on another side of the chamber, typically within the attachmentreceptacle 38. An exhaust needle 48 is also secured to the enclosure 32and will have an inlet end 50 dispose near but axially offset from theoutlet end 46 of the transfer needle since both the outlet end 46 andthe inlet end 50 must penetrate through the septum of a single recipientcontainer 56 as part of the fluid transfer procedure. An outlet end 52of the exhaust needle 48 will be positioned within the interior chamber36 and disposed to a release exhausted recipient liquid into anabsorbent mass 58 also located within the interior chamber 36. Inlet end44 of the transfer needle 42 will be available to penetrate the septumof a container 54 of the donor liquid which is to be transferred intothe recipient liquid in container 56.

Transfer of the donor liquid from container 54 into the recipient liquidin container 56 is typically achieved by displacing a plunger (notshown) on the donor container so that liquid flows through the transferneedle 42 into the interior of the recipient container 56. As therecipient container 56 will typically be completely filled with therecipient liquid, entry of the donor liquid will cause a like volume ofthe recipient liquid to be exhausted through the exhaust needle 48 andinto the absorptive mass 58 where it is sequestered and prevented fromleaking through the vents 40, backflows into the exhaust needle 48, orotherwise being lost. Of course, it will be understood that a smallportion of the donor liquid may be mixed in with the recipient liquidwhich is exhausted, but the amount of donor liquid in the exhaustedliquid will usually be minimized, typically by offsetting the inlet end50 of the exhaust needle 48 from the outlet end 46 of the transferneedle 42.

Referring now to FIGS. 3A-3C, the absorbent mass may have a variety ofgeometries intended to promote capture and sequestration the exhaustrecipient liquid so that the liquid is not allowed to backflow into theoutlet end 52 of exhaust needle 48 or leak into the interior chamber 36from where it might leak outside of the liquid transfer connector 30. Asshown in FIG. 3A, the absorbent mass could be a block with the outlet in52 of the exhaust needle 48 terminating generally at a mid or centerpoint within the mass. While having the advantage of being a simpledesign, the limited area of the mass exposed to the needle limitsrelease of the liquid and can cause back pressure and potential backflow of the liquid along the needle so that it is lost in the absorptivemass if the liquid transfer rate is too great.

Alternatively, the absorptive mass 58 may comprise absorbent beadshaving a size or shape which prevents passage through the vents. Theinterior chamber 36 may be loose packed with such beads and the verylarge surface area will result in rapid absorption of liquid released bythe exhaust needle 48. Typically the absorptive mass will be formed froma material that does not biologically and/or chemically react with therecipient liquid.

An alternative absorptive mass configuration is illustrated in FIG. 3Bwhere the exhaust needle 48 comprised a plurality of branches or ports60 along its length which distribute the exhausted recipient liquid to aplurality of locations within the absorptive mass, thus reducing theback pressure and allowing greater fluid transfer rates without leakage.Although an improvement, this design is more difficult to construct andimplement.

A presently preferred design for the absorptive mass 58 is illustratedin FIG. 3C. There, the absorptive mass comprises an outer block or shellsurrounding an interior void 62, where the outlet end 52 of the exhaustneedle 48 is located near an interior end 64 of the void but spaced wellapart from the side walls 66 of the void. This construction allows theliquid to enter freely (with minimum back pressure) into the void 62where it can be temporarily collected, distributed around the walls ofthe void, and absorbed into the absorptive mass 58 before having anopportunity to backflow into outlet end 52 of exhaust needle 48 orotherwise leak from the void. Optionally, a gas permeable liquid barrier68 may be formed over the open end of the void to further inhibit lossof free liquid from the void.

As shown in FIGS. 4A-4D, sequential absorption of volumes of displacedrecipient fluid exhausted through needle 48 into the absorptive mass 58of FIG. 3C is illustrated. Usually, a first volume of the exhaustedliquid is released into the interior void 62 from the outlet end 52 ofthe exhaust needle 48. The liquid will initially remain within the voidand distribute over portions of the end wall 64 and side wall 66. Thedistributed liquid will immediately begin to be absorbed into the masswhere it becomes sequestered and inhibited from release. The volume ofthe interior void 62 will be greater than that of the expected volume ofexhaust liquid expected to be released at any one time, typically beingat least twice the expected volume, and often being many times greater.After the first volume of exhausted liquid is absorbed into theabsorptive mass 48, the liquid will penetrate into the mass along aboundary line 72, as shown in FIG. 4B. Typically, the entire volume ofthe absorptive mass 58 will be many times greater than the expectedvolume of each release of exhaust liquid. Thus, multiple fluid transfersand exhaust liquid releases may be performed before it is time to eitherdispose of the liquid transfer connector or replace the absorptive masswithin the interior chamber 36. The release of a second volume of theexhaust liquid is illustrated in FIG. 4C. The liquid 74 will typicallydistribute along the back wall 64 and side walls 66 generally in thesame manner as in the first release. After the second volume isreleased, the peripheral absorption within the mass 58 will be greater,as illustrated at boundary line 76 in FIG. 4D.

Although particular embodiments of the present invention have beendescribed above in detail, it will be understood that this descriptionis merely for purposes of illustration and the above description of theinvention is not exhaustive. Specific features of the invention areshown in some drawings and not in others, and this is for convenienceonly and any feature may be combined with another in accordance with theinvention. A number of variations and alternatives will be apparent toone having ordinary skills in the art. Such alternatives and variationsare intended to be included within the scope of the claims. Particularfeatures that are presented in dependent claims can be combined and fallwithin the scope of the invention. The invention also encompassesembodiments as if dependent claims were alternatively written in amultiple dependent claim format with reference to other independentclaims.

1. A liquid transfer connector for providing a liquid transfer pathbetween a donor container having a needle-penetrable septum and arecipient container having a needle-penetrable septum, said connectorcomprising: an enclosure having an interior chamber with a vent; atransfer needle having an inlet end extending from one side of theinterior chamber and an outlet end extending from another side of thechamber, wherein both the inlet end and the outlet end are capable ofpenetrating a septum on a liquid container; an exhaust needle having aninlet end adjacent to the outlet end of the transfer needle and anoutlet end in the interior chamber; and a liquid-absorptive mass withinthe interior chamber, said absortive mass adapted for rapid absorptionof liquid entering the interior chamber through the exhaust needle.
 2. Aconnector as in claim 1, wherein the absorbent mass is at leastpartially formed from a liquid-absorptive foam.
 3. A connector as inclaim 2, wherein the liquid-absorptive foam has an absorptive rate lessthan 10 seconds as measured by IS09073-6-2000.
 4. A connector as inclaim 3, wherein the liquid-absorptive foam comprises a polyvinyl acetalresin.
 5. A connector as in claim 1, wherein the absorbent masscomprises a block of absorptive material having an interior void whichsurrounds the outlet end of the exhaust needle.
 6. A connector as inclaim 5, wherein the outlet end of the exhaust needle is spaced apartfrom walls of the interior void so that the exhausted recipient liquidcan pool in the void without submerging the inlet end.
 7. A connector asin claim 1, wherein the absorptive mass comprises absorbent beads havinga size or shape which prevents passage through the vents.
 8. A connectoras in claim 7, wherein the beads are loose and fill the interiorchamber.
 9. A connector as in claim 1, wherein the enclosure comprises acylindrical sleeve having a partition which separates an attachmentreceptacle that encloses the outlet end of the transfer needle and theinlet end of the exhaust needle from the interior chamber.
 10. Aconnector as in claim 1, wherein the transfer needle passes axiallythrough the liquid absorptive mass.
 11. A method for transferring adonor liquid into a recipient liquid present in a closed container, saidmethod comprising: establishing a transfer flow path from a source ofthe donor liquid into the closed container filled with the recipientliquid, establishing an exhaust flow path from the closed container toan absorbent mass; and causing a volume of the donor liquid to flow intothe closed container through the transfer flow path which in turn causesa like volume of the recipient liquid to flow through the exhaust flowpath into the absorbent mass, wherein the entire volume of the exhaustedrecipient liquid is absorbed by the absorbent mass.
 12. A method as inclaim 11, wherein the absorbent mass is at least partially formed from aliquid-absorptive foam.
 13. A method as in claim 12, wherein theliquid-absorptive foam has an absorptive rate less than 10 seconds asmeasured by IS09073-6-2000.
 14. A method as in claim 13, wherein theliquid-absorptive foam comprises a polyvinyl acetal resin.
 15. A methodas in claim 11, wherein the absorptive mass comprises absorbent beadshaving a size or shape which prevents passage through the vents.
 16. Amethod as in claim 15, wherein the beads are loose and fill the interiorchamber.
 17. A method as in claim 11, wherein the absorbent masscomprises a block of absorptive material having an interior void whichsurrounds the outlet end of the exhaust needle.
 18. A method as in claim11, wherein the absorptive mass has an absorptive capacity equal to atleast twice the volume of the exhausted recipient liquid.
 19. A methodas in claim 18, wherein the interior void has a volume equal to at leastthe volume of the exhausted recipient liquid and the absorptive mass hasan absorptive capacity equal to at least twice the volume of theexhausted recipient liquid.
 20. A method as in claim 17, wherein theoutlet end of the exhaust needle is spaced apart from walls of theinterior void so that the exhausted recipient liquid can pool in thevoid without submerging the outlet end.
 21. A method as in claim 11,wherein the absorptive mass comprises a material that does notbiologically or chemically react with the recipient liquid.